JP3377167B2 - Public space loudspeaker method and apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention collects a voice uttered by a speaker by a microphone array composed of a plurality of microphones, processes an output signal of the microphone array, and raises only the voice of the speaker. The present invention relates to an in-field loudspeaking method and a device using a single or a plurality of speakers that pick up sound at an SN ratio and radiate the picked up output signal as sound waves in the same room where the talker is located. In the field loudspeaking method and device, the influence of the speaker is removed to accurately detect the speaker, and the amplification of the speaker in the vicinity of the speaker is controlled to eliminate adverse effects such as howling. is there.

[0002]

2. Description of the Related Art Conventionally, in a public loudspeaker, a microphone is installed in the vicinity of a speaker or the speaker speaks with a microphone, the output signal from the microphone is amplified, and the speaker outputs the sound wave as a sound wave. It was common to radiate indoors.

However, in recent years, it has been a hindrance to install a microphone in the vicinity of the speaker, and the microphone must be handed to the interrogator when the question from the listener is raised in the hall at a lecture or the like. It is not necessary to install a microphone close to the speaker or the interrogator, because it is complicated to do, and it is possible to speak naturally without being aware of the microphone, and only the target sound such as voice is high. There is a demand for a sound pickup device that picks up sound at an SN ratio.

As an example of such a sound collecting device, there is a sound collecting device in which a plurality of microphones (microphone arrays) are installed, and the outputs of these microphones are subjected to signal processing to extract a target sound. The signal processing method for suppressing the noise and extracting the target speech using such a microphone array is a delay sum method,
Although many such as AMNOR are known (for example, Oga, Yamazaki, and Kaneda "Acoustic system and digital processing", The Institute of Electronics, Information and Communication Engineers, 1995, pp. 173-197), for example, in the delay-sum method, Extract sound.

FIG. 5 is a diagram for explaining the principle of target sound extraction by the delay sum method. In FIG. 5, 1 is a sound pickup unit (microphone array), 2 ₁ , 2 ₂ , ..., 2 _M is a microphone (M is the number of microphones), 3 ₁ , 3 ₂ , ...
.., 3 _M is a delay device, 4 is an adder, 5 is an output signal, 6 is a noise suppressing unit, d is a microphone interval, and s (t) is a sound wave arriving at the sound collecting unit 1 (t represents time). , Θ is an arrival angle at which the sound wave s (t) arrives at the sound collection unit 1, and τ, which will be described later, is a time difference (delay time) at which the sound wave arrives at each microphone.

The microphones 2 ₁ , 2 ₂ , ..., Of FIG.
It is assumed that 2 _M are arranged in a straight line at equal intervals d, and sound waves s (t) arrive from a distance to the linearly arranged microphones at an angle θ. At this time, the distance traveled by the sound wave s (t) reaching the microphone 2 ₁ before reaching the microphone 2 ₂ is ds from the microphone interval d and the arrival angle θ.
It is represented by in θ. Similarly, the i-th microphone 2 _i
The distance propagated before reaching (i = 2, ..., M) is represented by (i−1) d sin θ. Therefore, the delay time τ _i required to reach the microphone 2 _i (i = 2, ..., M) is calculated by dividing the propagation distance by the sound velocity c with reference to the microphone 2 ₁ , ).

[0007]

[Equation 1] Here, the output signal from each microphone 2 _i (i = 1, ..., M) is represented by x _i (t), which is the sound wave s.
Since (t) is delayed by τ _i , the following expression (2) is obtained.

[0008]

[Equation 2] Here, if the delay amount D _i of the delay device 3 _i (i = 1, 2, ..., M) is appropriately set, only the sound wave coming from the θ direction can be emphasized and output to the output signal 5 as follows. Shown in.

The delay amount D _i of the delay device 3 _i (i = 1, 2, ..., M) is set as in the following equation (3).

[0010]

[Equation 3] D _o is a fixed delay amount added in order to prevent the accuracy when the delay characteristic is realized by the digital filter from being lowered when the value of τ _i is too small.

At this time, the delay device 3 _i (i = 1, 2, ...
., M) is output as shown in the following expression (4) because the delay amount D _i of the expression (3) is generated in the signal of the expression (2).

[0012]

[Equation 4] That is, regardless of the microphone number i, s (t)
Becomes the same signal delayed by D ₀ .

If the signals are added up by the adder 4 after the phases are aligned in this way, the sound waves arriving from the θ direction are emphasized by the added amount. On the other hand, since the sound wave coming from the θ _N direction different from the θ direction is received with the delay time τ _N different from τ _i , the phases are not aligned with the delay amount of the equation (3), and the adder 4 Adding the signals together does not emphasize them.

In this way, in the delay sum system, the delay amount D
_By setting _i as in Expression (3), the sound wave coming from the target direction θ is emphasized, and the noise coming from the other direction θ _N is relatively suppressed.

At this time, if the target direction θ is scanned by changing the delay amount D _i and the output signal of the microphone array 1 is monitored, the output signal becomes large when θ is directed to the target speaker. Therefore, it is possible to find the direction of the target speaker. Then, the target sound is obtained by aligning and adding the phases according to the equation (4) so as to emphasize the sound wave from the direction θ of the target speaker, that is, by directing the directivity of the microphone array 1 in the direction of θ. Sound can be picked up with a high SN ratio.

Although a plurality of microphones 2 ₁ , 2 ₂ , ..., 2 _M are arranged on a straight line at equal intervals d for convenience of explanation, the microphones are not equally spaced. It is also possible to make it, and the shape to arrange is also 2
It may be arranged three-dimensionally or three-dimensionally.

Further, when the sound source S like a point sound source is located at a distance relatively close to the microphone array 1 as shown in FIG.
₁ , 3 ₂ , ..., 3 _M gains 7 ₁ , 7 ₂ , ...
······························· 7 _M , and applying an appropriate load to this gain is important for improving the sound collection SN ratio. As a method of giving a load, there is a way of giving the following equations (5), (6), (7) (Nomura, Kaneda, Kojima "Measure array of near field microphones", Journal of Acoustical Society of Japan, 53). Volume 2 (199
7), pp. 110-116).

[0018]

[Equation 5]

[0019]

[Equation 6]

[0020]

[Equation 7] Here, r ₁ , r ₂ , ..., R _M are the distances from the sound source S to the microphones 2 ₁ , 2 ₂ , ..., 2 _M , and r _C is the critical distance in the room, that is, the direct sound power of the sound source. It is a distance at which the reverberant sound power becomes equal, and r _C = √ (0.0032 V / for a room volume V [m 3] and a room reverberation time T [second]
(H.Kuttruff, “RoomAcoustics (Thir
d Edition) ”, Elsevier Applied Science, pp.100-132
(1991)). At this time, the microphone array 1 has the highest sensitivity with respect to the "point" of the position of the sound source S, so to speak, the "focus" of the sensitivity is formed. At this time, the distance r _i to each microphone (i = 1, 2, ...
- delayer 3 _1, 3 ₂ for M), · · ·, 3 _M delay amount _{D 0 -r i / c (c} : sound velocity) and the focal point of the gain g ₀ That sensitivity by changing the a above By scanning and monitoring the array output, the array output increases when the sensitivity focus is on the point where the target speaker is present, which allows the position of the target speaker to be found.

In this way, by finding the existence area of the target speaker as a direction or position and directing the array directivity to the existence area, the target sound can be collected with a high sound collection SN ratio.

Attempts will be made to apply this microphone array 1 to public address loudspeaker. As described above, the advantage of using the microphone array 1 for the sound pickup section of the public loud sound is that the high sound pickup S
Since it is possible to install the microphone array 1 at a position distant from the speaker with N ratio, it is not necessary to install the microphone close to the speaker, and the microphone is not conscious.
There are advantages such as natural calling. Another advantage is that it is not necessary to hand over the microphone to the questioner when raising the question from the listener into the venue at a lecture meeting.

FIG. 7 shows an example of a public address system using this microphone array as a sound pickup section. In this figure, 11 represents the entire public address system, 12 is a microphone array, and 13 is a microphone array.
Is a microphone array processing device, 14 is an amplifier, and 15 is a speaker. The uttered target voice is picked up by the microphone array 12, and the microphone array processing device 13
After the target sound is emphasized in (1), it is amplified by the amplifier 14 and is radiated as a sound wave in the field from the speaker 15. As described above, the microphone array processing device 13 scans the directivity of the microphone array 12 to find out the presence area of the target speaker, and operates so that the directivity of the array is directed to the presence area of the target speaker. High S
It operates to pick up sound at N ratio.

[0024]

As described above, the microphone array 12 detects the presence region of the target speaker and directs the array to this presence region to direct the target voice to a high S level.
It was effective in collecting sound at N ratio. But,
When the speaker voice of the speaker is radiated from the speaker 15, the speaker position or its vicinity is often detected as an area where the target speaker exists, and the directivity of the microphone array 12 is directed toward the speaker. I knew that I would end up.

In order to avoid this problem, if the directivity of the microphone array 12 is prohibited in the direction of the receiving speaker, when the speaker speaks at a position close to the speaker 15, the speaker exists. It was also found that the directivity of the microphone array 12 cannot be sufficiently directed to the region, and a new problem occurs that the target voice cannot be picked up with a sufficiently high SN ratio. Further, even if the directivity of the microphone array 12 can be directed to the speaker, a closed loop is formed in which the target voice radiated from the speaker 15 is picked up by the microphone array 12 again and amplified again. It was also found that howling was caused due to the cause, and that there was a problem that sufficient public address could not be obtained.

[0026]

In order to solve the above problems, the present invention controls an amplifier as follows.
That is, the speaker position detecting means for detecting the position of the speaker, the judging means for judging the speaker proximity speaker existing in the vicinity of the speaker position among the plurality of speakers installed in the room, and the speaker proximity speaker. A control means for controlling the gain of the amplification means connected to the speaker is provided, and when the speaker speaks, the control means controls so as to lower the gain of the amplification means connected to the speaker near the speaker.

The speaker is detected as follows. That is, a speaker sound collecting means that scans the directivity of the microphone array excluding the position of the speaker and a directivity of the microphone array that is directed to the vicinity of a region where the speaker sound collecting means forms the directivity. The speaker position is estimated using the sound collecting unit, the speaker sound collecting output signal output from the speaker sound collecting unit, and the comparison output signal output from the comparison sound collecting unit.

This position estimation is performed as follows, for example.
The speaker power calculation means for calculating the power of the output signal from the speaker sound collecting means, the comparison power calculation means for calculating the power of the output signal of the comparison sound collecting means, and the speaker power calculation means. Speaker power gradient determination means for determining whether the calculated speaker power exceeds the comparison power calculated by the comparison power calculation means by a set value and a threshold value W for which the speaker power is set If a speaker power determination means for determining whether or not the power exceeds the above is provided, the determination by the speaker per determination means is true, and the determination result of the speaker power gradient determination means is that a voice is uttered by the speaker. When the determination is made, the speaker position estimating means estimates the speaker position.

When the delay sum method shown in FIG. 5 or 6 is used as the signal processing for the microphone array output, the directivity is generally sharper in the high frequency range. Therefore, by using the high frequency components, the sound wave emitted from the speaker can be separated from the sound wave emitted from the speaker and collected even if the speaker is present near the speaker. The speaker position can be detected by distinguishing the target voice radiated from the person. The high frequency components can be extracted by passing the microphone array output for the speaker and the comparison focus through a high frequency filter. As described above, a specific band-pass filtering unit for the output signals from the speaker sound collecting unit and the comparison sound collecting unit is provided, and the speaker position estimating unit uses the output signal of the band filtering unit to make the speaker position estimating unit. Estimate the position.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, in the speaker position detecting means, the directivity of the microphone array is scanned as described above, and the position of the speaker is searched. At this time, the position of the speaker is excluded from the scanning target. However, even if the position of the speaker is removed from the scanning target, when the sound is emitted from the speaker, the sound pressure in the area near the speaker rises, so the detected position is based on the sound from the speaker. It is necessary to identify whether it is detected or detected based on the increase in sound pressure from the speaker. Therefore, the position of the speaker is accurately detected as follows. That is, in addition to the directivity of the microphone array toward the detected speaker area Fsp, the area Fi (i = 1, 2, ...
.., L) with directivity for comparison directed to array output Esp for region Fsp and array output E for region Fi
The speaker position is detected by comparing i (i = 1, 2, ..., L). However, the region Fi is the region Fsp and the region F.
It is assumed that the position is closer to the expected position of the speaker compared to i. When the voice is emitted from the speaker, the output Esp is highest, so Esp> Ei (i = 1, 2, ...
···, L). On the other hand, when sound is emitted from the speaker and the sound pressure is high, the area Fi is the area Fs.
Since it is closer to the speaker than p, Esp <Ei (i = 1,
2, ..., L). Therefore, Esp> Ei (i
= 1, 2, ... L), the speaker position can be detected as the position where the speaker emits the voice. In addition, in order to remove the influence of noise in the room,
In addition to the condition of Esp> Ei (i = 1, 2, ... L), it may be determined that the voice is uttered by the speaker when Esp exceeds a certain threshold value th.

Next, the determination means determines the speaker proximity speaker existing near the speaker position among the speakers, and when the speaker speaks, the control means amplifies the speaker connected to the speaker proximity speaker. It controls so that the gain of the means is lowered. Here, the directivity of the delay-sum array of FIG. 5 or 6 is generally sharp in the high range and wide in the low range. In other words, when a loudspeaker is used for loudspeaking, the amount of coupling in the low frequency range is large, which is a problem. Therefore, the low frequency component is attenuated with respect to the signal of the speaker near the speaker.

[0032]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention. In this figure, 21 is a public address system, which is a microphone array 22 and a microphone array processing device 23.
An amplifier (amplifying means) 24, a speaker 25, a speaker position detecting section (speaker position detecting means) 26, a judging section (judging means) 27, and a control section (control means) 28. .

Next, the operation will be described. The voice uttered by the speaker is picked up by the microphone array 22, the output signal of the microphone array 22 is signal-processed by the microphone array processing device 23, only the target sound is extracted, amplified by the amplifier 24, and output from the speaker 25 to the hall. Be loud. At this time, the speaker position detecting unit 26 detects the speaker position from the output signal of the microphone array 22, and the judging unit 27 determines the speaker position among the plural speakers 25 for public address loudspeaking based on the detected speaker position. Based on this determination, the control unit 28 lowers the gain of the amplifier 24 with respect to the speaker located closer to the speaker, and directs the microphone array 22 to the speaker located closer to the speaker 25. Even when the sound is heard, howling is prevented, and the target sound can always be amplified in the field with a high SN ratio.

FIG. 2 shows a second embodiment of the present invention. This is a speaker sound collecting unit (speaker sound collecting means) 31 for directing the directivity of the microphone array 22 to a speaker, and a comparison sound collecting unit for directing the directivity of the microphone array 22 in the vicinity of the speaker (for comparison). Sound collecting means) 32, and a speaker position estimating section (speaker position estimating means) 33 for estimating a speaker position using the output from the speaker sound collecting section 31 and the output from the comparison sound collecting section 32. This is an embodiment in which a speaker position detecting unit (speaker position detecting means) 26 is configured. According to this embodiment, the speaker position can be estimated more accurately.

FIG. 3 shows a third embodiment of the present invention. This is a speaker power calculation unit (speaker power calculation means) 34 that calculates the power of the output signal from the speaker sound collection unit 31.
And the power of the output signal from the comparison sound collecting unit 32, the comparison power calculation unit (comparison power calculation means) 35, and the talker power calculated by the talker power calculation unit 34 are the comparison power calculation unit 35. The speaker power gradient determining unit (speaker power gradient determining means) 36 for determining whether the power for comparison exceeds the comparison power calculated in step 36, and determines whether the speaker power exceeds the set threshold th. A speaker power determination unit (speaker power determination unit) 37 is provided, and the speaker power gradient determination unit 36 and the speaker power determination unit 37 are provided.
In this embodiment, the speaker position estimating unit 33 is configured to estimate the speaker position when both of the determinations are true.

FIG. 4 shows a fourth embodiment of the present invention. This is provided with a specific band-pass filter unit (band-pass filter unit) 41 of the outputs from the speaker sound collecting unit 31 and the comparative sound collecting unit 32, which is provided at the subsequent stage of the speaker sound collecting unit 31 and the comparative sound collecting unit 32. , The speaker position estimation unit 33 using the output signal of the band filtering unit 41.
Is an embodiment configured to measure the speaker position.

[0038]

As described above, according to the present invention,
Even when the speaker is located close to the speaker, the target voice can be picked up by directing the array to the region where the speaker is present. Further, when the speaker speaks in the vicinity of the speaker, the gain of the amplifying means connected to the speaker in the vicinity of the speaker is controlled to be lowered, so that howling can be avoided even when the directivity of the array is directed to the speaker. It has an unprecedented excellent effect that it can.

Then, with respect to the signal of the speaker near the speaker,
Since the low frequency components are attenuated, howling can be effectively suppressed.

In addition to the directivity of the microphone array to the area Fsp where the speaker exists, the speaker position detecting means also has an area Fi (i = 1, 2, 1) near the speaker and closer to the speaker than Fsp. , L: L directs the directivity for comparison to the number of focal points for comparison, and array output Esp for Fsp and array output Ei for Fi (i = 1, 2,
, L) is compared to detect the speaker position by detecting Esp> Ei, the speaker position is erroneously affected by the speaker even when the target speaker is pronouncing near the speaker. It is possible to prevent the determination. In addition, since the speaker position is detected by determining whether Esp exceeds the set threshold th, Esp> Ei due to background noise in the room.
Even in the case of (i = 1, 2, ... L), it is possible to prevent an erroneous determination of the speaker position, which is an excellent effect that has never been achieved.

Furthermore, since the speaker power calculation unit and the comparison power calculation unit calculate the powers of the output signals from the speaker sound collection unit and the comparison sound collection unit to determine the speaker position, An effect that an accurate determination can be performed is exhibited.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a third exemplary embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a fourth exemplary embodiment of the present invention.

FIG. 5 is a diagram for explaining the principle of noise suppression sound collection by the delay sum method.

FIG. 6 is a diagram for explaining how to appropriately set the load of the gain in the latter stage of the delay device and improve the sound pickup SN ratio when the sound source microphone is located at a position close to the microphone array.

FIG. 7 is a diagram for explaining in-field loudspeaking using a conventional microphone array.

[Explanation of symbols]

21 Public address system 22 microphone array 23 Microphone array processing device 24 amplifier 25 speakers 26 Speaker position detector 27 Judgment section 28 Control unit 31 Speaker sound pickup unit 32 Sound recording part for comparison 33 Speaker position estimation unit 34 Speaker power calculator 35 Comparison Power Calculation Unit 36 Speaker power gradient determination unit 37 Speaker power determination unit 41 bandpass filter

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-8-288999 (JP, A) JP-A-63-301653 (JP, A) JP-A-56-39669 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H04R 3/02 H04R 1/40 320 H04R 3/00 310

Claims (9)

(57) [Claims] 1. A microphone array comprising a plurality of microphones, a microphone array device for processing an output signal of the microphone array, and a single or a plurality of speakers for amplifying an output signal of the microphone array device and radiating the same as a sound wave. In the method for in- situ loudspeaker provided with the in- situ loudspeaker, the microphone position is excluded except the position of the speaker.
A speaker sound collecting means for scanning the directivity of the ray, and the speaker sound collecting means.
The microphone is placed near the area where the sound means forms directivity.
A sound collecting device for comparison, which directs the array, and a speaker collecting device.
Speaker sound output signal which is the output from the sound means and the ratio
Using the comparison output signal which is the output from the comparison sound collecting means
From the speaker position estimating means for estimating the speaker position by
An on-site loudspeaking method characterized in that a speaker position is detected to detect a speaker and lower the gain of a speaker existing in the vicinity of the speaker. 2. The on-site loudspeaker method according to claim 1 , wherein the speaker power calculation means for calculating the power of the output signal from the speaker sound collecting means and the output signal of the comparison sound collecting means. Comparing power calculation means for calculating power, and utterance for judging whether or not the speaker power calculated by the speaker power calculation means exceeds the comparison power calculated by the comparison power calculation means by a set value Power gradient determining means and speaker power determining means for determining whether or not the speaker power exceeds a set threshold value, the determination of the speaker power determining means is true, and the speaker power is An in-field loudspeaking method, wherein the speaker position estimating means estimates the speaker position when the determination result of the gradient determining means determines that a voice is uttered by the speaker. 3. The on-site loudspeaker method according to claim 1 or 2 , wherein a band for extracting a specific band component of an output signal from the speaker sound collecting means and the comparison sound collecting means. An in-field loudspeaking method , characterized in that filtering means is provided, and the speaker position estimating means estimates the speaker position using the output signal of the band filtering means. 4. A microphone array comprising a plurality of microphones, a microphone array device for processing an output signal of the microphone array, and a single or a plurality of speakers for amplifying an output signal of the microphone array device and radiating the sound signal as a sound wave. in hall loudspeaker method of hall loudspeaker apparatus having, hall loudspeaker wherein the attenuating detects speaker, a low-frequency component of the speaker which exists in the vicinity of the speaker. 5. A microphone array including a plurality of microphones, a microphone array processing device for processing an output signal of the microphone array, an amplifying means for amplifying an output signal of the microphone array processing device, and an output of the amplifying means. in hall public address system comprising a single or a plurality of speakers which emits a signal as a sound wave, a speaker position detection means for detecting a speaker position, calling speaker near a speaker which exists in the vicinity of the emitting speaker position of the speaker determining means for determining, a field within loudspeaker apparatus provided with a control means for controlling the gain of the amplifying means connected to該話's near speaker, said except for the position of the speaker microphone
Speaker sound collecting means for scanning the directivity of the array, and the utterance
The microphone is placed near the area where the sound pickup means forms directivity.
A sound collecting device for comparison which directs the directivity of the hon array, and the utterance.
The speaker sound collection output signal which is the output from the person sound collecting means, and
And a comparison output signal which is an output from the comparison sound collecting means.
From the speaker position estimation means for estimating the speaker position using
Inside the hall characterized by comprising the speaker position detecting means
Loudspeaker. 6. A microphone array including a plurality of microphones, a microphone array processing device for processing an output signal of the microphone array, an amplifying means for amplifying an output signal of the microphone array processing device, and an output of the amplifying means. in hall public address system comprising a single or a plurality of speakers which emits a signal as a sound wave, a speaker position detection means for detecting a speaker position, calling speaker near a speaker which exists in the vicinity of the emitting speaker position of the speaker An in-field loudspeaker system comprising: a determination unit that determines whether or not the low-frequency component is attenuated before or after the amplification unit that is connected to the speaker near the speaker. 7. The loudspeaker according to claim 6 , wherein the speaker sound collecting means for scanning the microphone array for directivity except the position of the speaker, and the speaker sound collecting means for directivity. The sound collection means for comparison which directs the directivity of the microphone array in the vicinity of the region forming the sound source, the speaker sound collection output signal output from the sound collection means for speaker and the output from the sound collection means for comparison. An on-site loudspeaker, characterized in that the speaker position detecting means is composed of a speaker position estimating means for estimating the speaker position using a certain output signal for comparison. 8. The public address system according to claim 5 or 7.
And the power of the output signal from the speaker sound collecting means is
Of the speaker power calculating means for calculating and the comparing sound collecting means.
A comparison power calculation means for calculating the power of the output signal,
The speaker power calculated by the speaker power calculation means is
Than the comparative power calculated by the comparative power calculation means
Speaker power gradient judgment to determine whether the value exceeds the set value
Constant means and the speaker power exceeds the set threshold value.
A speaker power determining means for determining whether the
If the determination made by the speaker power determination means is true and the speaker power is
The result of the slope determination means is that the speaker uttered a voice.
When it is determined that the speaker position is estimated,
A public address system that estimates the position of a person. 9. Public loudspeaker according to claim 5, 6 or 8.
A device, the speaker sound collecting means and the comparative sound collecting means
Band for extracting a specific band component of the output signal from
Filtering means is provided, and the output signal of the band-pass filtering means is used to
The speaker position estimating means estimates the speaker position.
A public address system.